Decisions in the brain

Featured image caption: Ming Hsu running a behavioral experiment in the Xlab.

By Chris Holdgraf

Every second, billions of people across the world make a decision. How to dress for the day, whether to go back to school, where to find your next meal, whether you want to go on that second date – the choices we make in life have a significant impact on our own lives, and on the lives of others.

However, studying just how we decide is notoriously difficult. For centuries, scholars of the world have attempted to understand what makes us choose one option over another, and what makes some people jump to action while others hesitate. Though such questions are quite old, we have come away with only a tiny understanding of the complexity of our human decision-making machinery.

In the last century, interest in understanding how we decide has continued to grow. Economists, psychologists, and sociologists have studied our behavioral patterns, even quantifying our behavior with mathematical models, and we have learned a lot in the process. However, we still don’t understand the most important decision-making tool that we’ve got: our brain. Ming Hsu, member of the Helen Wills Neuroscience Institute and assistant professor at UC Berkeley’s Haas School of Business, hopes to change all of that.


Linking our choices to our brains


Trained jointly as an economist and a neuroscientist, Hsu is on the forefront of a rapidly growing field known as “neuro-economics.” This field asks the basic question, what does learning about the brain tell us about how we make decisions? It covers a wide range of topics, attempting to link neurobiology to the every-day actions that we take. For example: Is there a particular region of the brain that acts as a “decider” for everything else? Do different locations process risks and rewards? How is information transferred from one brain area to another when we decide? There is a long list of unanswered questions to be tackled.

In order to join these two fields, Hsu attempts to map certain behaviors onto patterns of activity in the brain. He accomplishes this by combining age-old practices in behavioral psychology and economics with the cutting-edge technology for brain imaging that has emerged in the last fifteen years.


How to test our decisions


While it may seem simple to test our decision-making skills (just make them decide something!), it is quite difficult to tease out such a complex process. The basic approach is this: come up with a decision-making mechanism that you want to understand (say, dividing an apple pie between yourself and others). Think about the core psychological and economic components that might go into this decision (How hungry am I? How much should I share with other people? Will I meet them again?). Finally, design an experiment that isolates these core behavioral components, and record a person’s brain activity as they complete your task.

Perhaps unsurprisingly, tasks like these require a wide range of processes, and what results is a fascinating dance of planning, comparing, and competition amongst brain regions. One spot may respond particularly to moral quandaries, while another is responsible for deciding how much you’d benefit from that slightly bigger piece of pie. These neural signals get bounced back and forth any time you make a decision, and Hsu ties them down to particular moments in the decision-making process.

Once they have a good lead for a particular neural pathway in decision-making, the Hsu lab next attempts to control this pathway through pharmacologic manipulation (using drugs alter our behavior). For example, recent research suggests that dopamine – one of the most common chemical compounds in the brain – has a strong impact on risk assessment. The Hsu lab might give people a drug that increases the level of dopamine circulating throughout the brain. His team then asks subjects to perform a task in which they must choose between a more reliable decision that pays less, or a riskier choice that pays more. The lab determines if people make different choices with increased dopamine levels, and looks for changes in activity across brain areas that are traditionally associated with dopamine and decision-making.


From the lab to society


A better understanding of how we (and our brains) make decisions has enormous implications for many parts of our society, and the Hsu lab hopes that their findings will be useful to doctors, businesses, and governments around the world. One of the most common problems with decision-making is that often, we don’t do it well. Moreover, both governments and businesses are constantly confronted with questions of how to make the right choices, and Hsu’s research is a unique new take on how to make choices effectively.

By understanding the neural mechanisms that govern our choices, it may be possible to assist those with difficulties in deciding (e.g., addicts deciding to stay sober). By researching the effects of pharmacological treatments, the Hsu lab also paves a pathway to medicine that may improve our ability to make good choices.

Ultimately, we are far from a complete picture of how and why people make the decisions they do. The brain is an incredibly complicated tool, and making decisions involves synthesizing and weighing many different kinds of data. For Hsu and his lab, there will always be more questions to ask, more thought experiments to run, and more ways of manipulating the decision-making processes we use every day. Who knows where they’ll decide to go next.


Read about some of the Hsu lab’s latest research discoveries:

Altering brain chemistry makes us more sensitive to inequality

Your genes affect your betting behavior

Study links honesty to prefrontal region of the brain